1. Field of the Invention
The present invention relates to a mechanism for seriatim positioning each frame of a photographic film in an exposure position behind an exposure aperture by advancing the photographic film by one-frame amount and for cocking a shutter actuating member during the one-frame advance of the photographic film, wherein the photographic film has one or two perforations per frame which are brought into engagement with the mechanism for the positioning and/or cocking.
2. Related Art
A photographic film has been known, for example, from JPA 3-179442, that is provided with magnetic recording tracks and has only one or two perforations per frame so as to permit efficient recording of data on the recording tracks outside the frames.
For use with such a photographic film, it is convenient to detect the perforation by a photo-sensor for controlling a motor to advance the photographic film by one-frame amount, and to cock the shutter by the power of the motor. However, to use such a photographic film in a low-price camera or a lens-fitted photographic film unit such as called "Quick Snap" (a trade name), for instance, because the cost of these article must be lower, it is unreasonable to mount the photographic sensor and the motor therein. In this case, it is necessary to mechanically detect the position of the perforations, mechanically advance the photographic film and mechanically cock the shutter.
As an example of those cameras which are loaded with photographic film having a perforation per frame, 110 camera using 110 film cartridge has been known. Also a lens-fitted photographic film unit, hereinafter referred to as film unit, which is pre-loaded with a 110 film cartridge is disclosed in JPU 63-51329. A conventional frame positioning and shutter cocking mechanism used in the conventional 110 camera or the 110 type film unit, has an arresting claw which is biased toward the film in a substantially perpendicular direction to the film surface. When the film is advanced by winding up the film to move the perforation in front of the arresting claw, the arresting claw is jumped into the perforation. Further film advance causes the arresting claw to move along with the film in a substantially rectilinear direction, thereby cocking the shutter.
The arresting claw is stopped against a stop pin at a predetermined position where the arresting claw still engages with the perforation. As a result, the film advance and the film winding is hindered. When a shutter release button is depressed, the arresting claw is disengaged from the perforation in the substantially perpendicular direction and, immediately thereafter, a shutter blade is actuated to make an exposure. When the shutter release button is returned to an initial position, the arresting claw is pressed onto the film surface under the biasing force, thereby the mechanism being ready for the next frame positioning and shutter cocking operation.
As described above, the arresting claw of the conventional frame positioning and shutter cocking mechanism always moves substantially linearly, that is, perpendicularly to the film surface when pressed onto and removed from the film surface, and along a straight film advancing path during clocking the shutter.
However, because it is necessary to keep engagement between the arresting claw and the perforation throughout the shutter cocking operation, the conventional frame positioning and shutter cocking mechanism is hardly applicable to such a film unit like as "Quick Snap" that makes the film surface concave about the exposure position. In that case, the arresting claw would slip off the perforation during the shutter cocking. Even after the shutter cocking, if the arresting claw should slip off the perforation before the shutter release, the photographic film would be vibrated by the shutter release operation, which could result in taking a duplicate or blurred picture.
Moreover, because the conventional mechanism requires a large number of parts including a lot of sliding member and a complicated mechanism for actuating the arresting claw, it would make it difficult to automatically assemble the film unit and thus increase the cost of the film unit.